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1
Machida, Kenji, and Yoshimasa Suzuki. "Examination of Accuracy of the Singular Stress Field Near a Crack-Tip by Digital Image Correlation." Key Engineering Materials 321-323 (October 2006): 32–37. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.32.
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Displacements obtained experimentally normally are including errors that make it impossible to extract stresses strains with high accuracy using the raw displacement data. In the infinitesimal deformation within the elastic region of a steel or an aluminum alloy, the quantity of displacement is less than 1 pixel, and analysis accuracy deteriorates. We have developed a system which employs the 2-D intelligent hybrid method and can analyze the displacement more exactly in the sub-pixel field. By using the Newton-Raphson method in conjunction with 2nd order deformation gradients, it is demonstrated that this method can accurately extract stress intensity factors from a set of measured displacements.
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Taoutioui, Abdelmalek, and Hicham Agueny. "Femtosecond Single Cycle Pulses Enhanced the Efficiency of High Order Harmonic Generation." Micromachines 12, no. 6 (May 26, 2021): 610. http://dx.doi.org/10.3390/mi12060610.
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High-order harmonic generation is a nonlinear process that converts the gained energy during light-matter interaction into high-frequency radiation, thus resulting in the generation of coherent attosecond pulses in the XUV and soft x-ray regions. Here, we propose a control scheme for enhancing the efficiency of HHG process induced by an intense near-infrared (NIR) multi-cycle laser pulse. The scheme is based on introducing an infrared (IR) single-cycle pulse and exploiting its characteristic feature that manifests by a non-zero displacement effect to generate high-photon energy. The proposed scenario is numerically implemented on the basis of the time-dependent Schrödinger equation. In particular, we show that the combined pulses allow one to produce high-energy plateaus and that the harmonic cutoff is extended by a factor of 3 compared to the case with the NIR pulse alone. The emerged high-energy plateaus is understood as a result of a vast momentum transfer from the single-cycle field to the ionized electrons while travelling in the NIR field, thus leading to high-momentum electron recollisions. We also identify the role of the IR single-cycle field for controlling the directionality of the emitted electrons via the IR-field induced electron displacement effect. We further show that the emerged plateaus can be controlled by varying the relative carrier-envelope phase between the two pulses as well as the wavelengths. Our findings pave the way for an efficient control of light-matter interaction with the use of assisting femtosecond single-cycle fields.
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Wang, Ya-Qiong, Shao-Bing Zhang, Long-Long Chen, Yong-Li Xie, and Zhi-Feng Wang. "Field monitoring on deformation of high rock slope during highway construction: A case study in Wenzhou, China." International Journal of Distributed Sensor Networks 15, no. 12 (December 2019): 155014771989595. http://dx.doi.org/10.1177/1550147719895953.
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In order to study the deformation stability of rock slope during the excavation of cutting slope and ensure the safety of rock slope during construction and operation period, this article analyzed the deformation law of a typical slope excavation by monitoring the surface deformation and the internal displacement of the rock mass. The surface deformation of the slope is monitored by setting monitoring points, and the internal deformation of the slope is monitored by installing multipoint displacement meters and inclinometers. Therefore, the relationship between slope excavation and deformation is obtained. The analysis of monitoring results shows that the slope is stable before excavation, and the displacement of the slope is gradually increased with the slope excavation. After the excavation, the displacement of each slope tends to converge. The maximum displacement in surface monitoring points is 12.30 mm, and the displacement parallels to the direction of the expressway. The maximum vertical displacement in surface monitoring points is 10.60 mm which occurred in the third step; the maximum internal displacement is 11.02 mm which mainly occurs in the weak structural plane of the rock boundary. During the excavation of the weak rock slope, the slope rock mass is prone to large displacement deformation. After the excavation, the slope surface displacement and internal displacement tend to converge in a short time.
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Felippa, Carlos A. "The Extended Free Formulation of Finite Elements in Linear Elasticity." Journal of Applied Mechanics 56, no. 3 (September 1, 1989): 609–16. http://dx.doi.org/10.1115/1.3176135.
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The free formulation of Bergan and Nyga˚rd (1984) has been successfully used in the construction of high-performance finite elements for linear and nonlinear structural analysis. In its original form the formulation combines nonconforming internal displacement assumptions with a specialized version of the patch test. The original formulation is limited, however, by strict invertibility conditions linking the assumed displacement field to the nodal displacements. The present paper lifts those restrictions by recasting the free formulation within the framework of a mixed-hybrid functional that allows internal stresses, internal displacements, and boundary displacements to vary independently. This functional contains a free parameter and includes the potential energy and the Hellinger-Reissner principles as special cases. The parameter appears in the higher-order stiffness of the element equations.
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Okada, H., H. Rajiyah, and S. N. Atluri. "A Novel Displacement Gradient Boundary Element Method for Elastic Stress Analysis With High Accuracy." Journal of Applied Mechanics 55, no. 4 (December 1, 1988): 786–94. http://dx.doi.org/10.1115/1.3173723.
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The boundary element method (BEM) in current usage, is based on the displacement boundary integral equation. The current practice of computing stresses in the BEM involves the use of a two-tier approach: (i) numerical differentiation of the displacement field at the boundary, and (ii) analytical differentiation of the displacement integral equation at the source point in the interior. A new direct integral equation for the displacement gradient is proposed here, to obviate this two-tier approach. The new direct boundary integral equation for displacement gradients has a lower order singularity than in the standard formulation, and is quite tractable from a numerical view point. Numerical results are presented to illustrate the advantages of the present approach.
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Guan, Kai Sen, Yu He Li, Yan Xiang Chen, and Yong Rong Qiu. "A Novel Optical Fiber Displacement Measurement System." Applied Mechanics and Materials 599-601 (August 2014): 684–88. http://dx.doi.org/10.4028/www.scientific.net/amm.599-601.684.
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In order to meet the displacement measurement’s need for high precision and large measuring range, a novel design of optical fiber displacement system is proposed. Optical fiber is applied to the displacement measurement field with its simple structure, light weight, cheap cost and high precision. A displacement measurement model based on transmissive optical fiber is established, and theoretical calculation and simulation are conducted to verify the accuracy of the model. Displacement measuring experiments are completed and the results show that the transmissive optical fiber displacement measurement system has high measuring accuracy with the relative error less than 0.2% over a large range.
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Mikhaylenko, Andrey, Natalie Rauter, Nanda Kishore Bellam Bellam Muralidhar, Tilmann Barth, Dirk A. Lorenz, and Rolf Lammering. "Numerical Analysis of the Main Wave Propagation Characteristics in a Steel-CFRP Laminate Including Model Order Reduction." Acoustics 4, no. 3 (June 25, 2022): 517–37. http://dx.doi.org/10.3390/acoustics4030032.
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Guided ultrasonic waves are suitable for use in the context of structural health monitoring of thin-walled, plate-like structures. Hence, observing the wave propagation in the plates can provide an indication of whether damage has occurred in the structure. In this work, the wave propagation in fiber metal laminate consisting of thin steel foils and layers of carbon fiber-reinforced polymer is studied, focusing on the main propagation characteristics like dispersion diagrams and displacement fields. For this purpose, the dispersion diagrams derived from the analytical framework and numerical simulations are first determined and compared to each other. Next, the displacement fields are computed using the global matrix method for two excitation frequencies. The results derived from the analytical framework is used to validate the numerically determined displacement fields based on a 2D and a 3D modeling approach. For both investigations the results of the analytical treatment and the numerical simulation show good agreement. Furthermore, the displacement field reveals the typical and well-known characteristics of the propagation of guided waves in thin-walled structures. Since the use of full 3D models involves a very high computational cost, this work also successfully investigates the possibility for model order reduction to decrease the computational time and costs of the simulation without the loss of accuracy.
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Guo, Qi Feng, Fen Hua Ren, and Zhao Cai Zhang. "Stabality Analysis of Deep Roadway Based on Coupled Thermo-Hydro-Mechanical Behaviors." Advanced Materials Research 594-597 (November 2012): 2564–68. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.2564.
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In order to research the stability of excavation in deep mines under high ground stress, high rock temperature and high karst hydraulic, the interaction of stress field, seepage field and temperature field are discussed through basic constitutive relation, seepage equation, thermometer equation and coupled thermo-hydro-mechanical equation. A numerical model was built to simulate the excavation of deep roadway. The result shows that the simulated ground stress based on three fields coupled is much closer to the field measured value and the change of stress and displacement caused by the excavation are limited which is about same as the later monitoring.
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Wang, Changsheng, Xiaoxiao Sun, Xiangkui Zhang, and Ping Hu. "High-order quasi-conforming triangular Reissner-Mindlin plate element." Engineering Computations 35, no. 8 (November 5, 2018): 2722–52. http://dx.doi.org/10.1108/ec-11-2017-0446.
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PurposeA higher-order Reissner-Mindlin plate element method is presented based on the framework of assumed stress quasi-conforming method and Hellinger-Reissner variational principle. A novel six-node triangular plate element is proposed by utilizing this method for the static and free vibration analysis of Reissner-Mindlin plates.Design/methodology/approachFirst, the initial assumed stress field is derived by using the fundamental analytical solutions which satisfy all governing equations. Then the stress matrix is treated as the weighted function to weaken the strain-displacement equations after the strains are derived by using the constitutive equations. Finally, the arbitrary order Timoshenko beam function is adopted as the string-net functions along each side of the element for strain integration.FindingsThe proposed element can pass patch test and is free from shear locking and spurious zero energy modes. Numerical tests show that the element can give high-accurate solutions, good convergence and is a good competitor to other models.Originality/valueThis work gives new formulations to develop high-order Reissner-Mindlin plate element, and the new strategy exhibits advantages of both analytical and discrete methods.
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Li, Peng Fei, Yuan Yuan, and Hong Zhao Liu. "Beam Element Considering the Warping Effect of Cross Section in Large Displacement Finite Element Analysis." Applied Mechanics and Materials 152-154 (January 2012): 958–63. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.958.
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A simple two-dimensional shear deformable finite beam element is developed in order to examine the effect of the high order interpolation on the modes of deformation of the beam cross section using the ANCF finite element. The new element allows for effect of warping that cannot be captured using previously introduced ANCF beam elements, and relaxes the assumption of planar cross section. The displacement field of the new element is assumed to be cubic in the axial direction and quadratic in the transverse direction. Using this displacement field, new shape functions are formulated and include the quadratic of the transverse direction instead of the linear expression. The displacement gradient and transverse strain component obtained using the new higher order element are introduced. Numerical example is presented in order to compare the results obtained using the new finite element and the results obtained using previously developed ANCF finite element. The results reveal that the cross section remains as a curve surface not a planar one.
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Xie, Yao Feng, Wei Qing Tang, and Jie Ping Tang. "Analysis of the Working Characteristics of High-Pile Wharf Pile Foundation under Berthing Load." Applied Mechanics and Materials 256-259 (December 2012): 1946–51. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.1946.
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In order to study the working characteristics of high-pile wharf pile foundation under berthing load, our team conducted the field test and established the numerical models. Analyzing the data from the test and models, the relationship between load and displacement of piles was deduced primarily. It’s proven to be usability.
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Pinto Correia, I. F., Cristovão M. Mota Soares, Carlos A. Mota Soares, and J. Herskovits. "Active control of axisymmetric shells with piezoelectric layers: a mixed laminated theory with a high order displacement field." Computers & Structures 80, no. 27-30 (November 2002): 2265–75. http://dx.doi.org/10.1016/s0045-7949(02)00239-0.
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Machida, Kenji, and Kazuhiro Okazaki. "Accuracy of Measurement of the Infinitesimal Deformation in Digital Image Correlation and the Intelligent Hybrid Method." Key Engineering Materials 353-358 (September 2007): 3096–99. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.3096.
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The displacement obtained from the experiment is including large error and it is impossible to evaluate the stress and the strain with high accuracy using raw displacement data. The 2-D intelligent hybrid method was applied in order to evaluate the 2-D stress field. In the infinitesimal deformation within elastic region of steel or an aluminum alloy, the quantity of displacement is less than 1 pixel, and analysis accuracy deteriorates. We need the system which can analyze the displacement more exactly in sub-pixel field. Hence, the Newton-Raphson method was applied after obtaining the displacement at any point of the image. On uniform deformation field, the infinitesimal strain was estimated with less than 0.01pixels of an error by DIC by taking into consideration only the 1st deformation gradient in the Newton Raphson method. On nonuniform deformation near the crack tip, it was estimated with about 0.018pixels error by taking the 2nd deformation gradient into consideration.
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Wang, Xian Quan, Hong Guang Zhang, Yi Tan Lei, Gui Lin Zhu, and Yao Yu. "Design and Simulation Analysis of Two-Phase Grating-Type Displacement Sensors with Unequal-Pitch." Applied Mechanics and Materials 631-632 (September 2014): 548–52. http://dx.doi.org/10.4028/www.scientific.net/amm.631-632.548.
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With the development of grating displacement sensors towards higher precision and higher speed of dynamic responses, the traditional design structure is hard to solve the processing difficulty of the increasing number of poles for time grating sensors. In order to realize the analysis on the internal magnetic field distribution of high precision displacement sensor, the unequal pitch grating displacement sensor with two phase model is established using Ansoft Maxwell simulation environment. The feasibility of the two unequal pitch grating displacement sensor and magnetic field simulation are performed based on the proposed sensor model. In addition the detailed synthetic method is proposed for the simulation data. The analysis show the feasibility of the unequal pitch grating displacement sensor with two phase. The proposed displacement sensor decreases the difficulties of machining process technology and increase the pole number. As the result, the measuring precision is improved.
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Li, Jin, Jing Wu, and Jia Qi Ren. "High Order Numerical Study of Gas Squeeze Film with Flexural Boundary Condition." Applied Mechanics and Materials 152-154 (January 2012): 462–67. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.462.
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Ultrasonic levitation system based on Near Field Acoustic Levitation is investigated in this study. A disc is levitated at a height much smaller than the acoustic wavelength where NFAL effect is dominant. A high-order analytical and numerical study on the levitation force induced by gas squeeze film is performed. By taking into account the modal solution on the vibrator whose disunity of the surface displacement can not be ignored, detailed boundary condition of gas squeeze film can achieve a high accuracy in final calculations of time-averaged pressure distribution, load capacity and stiffness of the system. A finite element analysis is compared with analytical solution. By discussing NFAL behavior in gas squeeze films, explanation of essential levitation characters in flexural vibrators is presented, which is important for future study on wafer’s non-contact transportation based on acoustic levitation.
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Lesieutre, G. A., and E. Bianchini. "Time Domain Modeling of Linear Viscoelasticity Using Anelastic Displacement Fields." Journal of Vibration and Acoustics 117, no. 4 (October 1, 1995): 424–30. http://dx.doi.org/10.1115/1.2874474.
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A time domain model of linear viscoelasticity is developed based on a decomposition of the total displacement field into two parts: one elastic, the other anelastic. The anelastic displacement field is used to describe that part of the strain that is not instantaneously proportional to stress. General coupled constitutive equations for (1) the total and (2) the anelastic stresses are developed in terms of the total and anelastic strains, and specialized to the case of isotropic materials. A key feature of the model is the absence of explicit time dependence in the constitutive equations. Apparent time-dependent behavior is described instead by differential equations that govern (1) the motion of mass particles and (2) the relaxation of the anelastic displacement field. These coupled governing equations are developed in a parallel fashion, involving the divergence of appropriate stress tensors. Boundary conditions are also treated: the anelastic displacement field is effectively an internal field, as it is driven exclusively through coupling to the total displacement, and cannot be directly affected by applied loads. In order to illustrate the use of the method, model parameters for a commonly-used high damping polymer are developed from available complex modulus data.
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Aketagawa, Masato, and Thanh Dong Nguyen. "Picometer mechanical displacement measurement using heterodyne interferometer with phase-locked loop." EPJ Web of Conferences 238 (2020): 06003. http://dx.doi.org/10.1051/epjconf/202023806003.
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In this paper, we show picometer-order mechnical displacmment measurements using a heterodyne interferometer with a phase-locked loop (PLL). A heterodyne light source for the interferometer is implemented with a frequency stabilized HeNe laser and two acousto-optic modulators. A real time phase measurement is performed by the PLL, whose software is programmed in a field-programmable gate array (FPGA). A stiff parallel spring stage combined with a high-voltage piezoelectric actuator is used to generate picometer-order mechanical motion. With the above implementations, mechanical displacement of 10 picometer or less can be measured.
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Li, Wanming, Ximin Zang, Haiyang Qi, Dejun Li, and Xin Deng. "Research on the ingot shrinkage in the electroslag remelting withdrawal process for 9Cr3Mo roller." High Temperature Materials and Processes 38, no. 2019 (February 25, 2019): 672–82. http://dx.doi.org/10.1515/htmp-2019-0014.
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AbstractIn order to reduce the air gap between ingot and mould in the electroslag remelting withdrawal (ESRW) process, the taper of the mould should be consistent with the ingot shrinkage.Athree-dimensional mathematical model was developed to describe the interaction of multiple-physical fields (Joule heat, electromagnetic field, velocity field, and temperature field) and ingot shrinkage during the ESRW process. The variations of material thermal and mechanical properties, as well as the yield function with temperature, were considered. The shrinkage behavior of 9Cr3Mo roller in the ESRW process was simulated using the sequential coupling method. A good agreement between the calculated value and the measured valuewas obtained in the temperature field and stress field. Numerical results showed that maximum values of current density, Joule heat, and electromagnetic forcewere at the electrode corner of the slag bath. The direction of the magnetic flux density was tangential to the slag bath and had a clockwise rotation. There were two pairs of vortices and two high temperature zones in the slag bath. The shrinkage displacement was obtained through thermal-stress analysis. As the distance from the mould outlet decreases, the shrinkage displacement of ingot increases. As for the electroslag remelting withdrawal process for 9Cr3Mo roller, the variation of the shrinkage displacement from the slag/metal interface to the mould outlet was 0.0028 m. The maximum shrinkage displacement is at the mould outlet, and the value was 0.0089 m.
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Wang, Hui, and Qing-Hua Qin. "Voronoi Polygonal Hybrid Finite Elements with Boundary Integrals for Plane Isotropic Elastic Problems." International Journal of Applied Mechanics 09, no. 03 (April 2017): 1750031. http://dx.doi.org/10.1142/s1758825117500314.
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Polygonal finite elements with high level of geometric isotropy provide greater flexibility in mesh generation and material science involving topology change in material phase. In this study, a hybrid finite element model based on polygonal mesh is constructed by centroidal Voronoi tessellation for two-dimensional isotropic elastic problems and then is formulated with element boundary integrals only. For the present [Formula: see text]-sided polygonal finite element, two independent fields are introduced: (i) displacement and stress fields inside the element; (ii) frame displacement field along the element boundary. The interior fields are approximated by fundamental solutions so that they exactly satisfy the governing equations to convert element domain integral in the two-field functional into element boundary integrals to reduce integration dimension. While the frame displacement field is approximated by the conventional shape functions to satisfy the conformity requirement between adjacent elements. The two independent fields are coupled by the weak functional to form the stiffness equation. This hybrid formulation enables the construction of [Formula: see text]-sided polygons and extends the potential applications of finite elements to convex polygons of arbitrary order. Finally, five examples including patch tests in square domain, thick cylinder under internal pressure, beam bending and composite with clustered holes are provided to illustrate convergence, accuracy and capability of the present Voronoi polygonal finite elements.
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Lu, Tao, Apostolos Tsouvalas, and Andrei Metrikine. "In-plane vibration of rotating rings using a high order theory." MATEC Web of Conferences 211 (2018): 03012. http://dx.doi.org/10.1051/matecconf/201821103012.
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In-plane dynamics of rotating rings on elastic foundation is a topic of continuous research, especially in the field of tire dynamics. When the inner surface of a ring is connected to a stiff foundation, the through-thickness variation of radial and shear stress needs to be accounted for. This effect is often overlooked in the ring models proposed in the literature. In this paper, a new high order theory is developed for the in-plane vibration of rotating rings whose inner surface is connected to an immovable hub by distributed springs while the outer surface is stress-free. The high-order terms are chosen such that the boundary conditions at the inner and outer surfaces are satisfied at all times. Instability, which is usually overlooked in the literature, is predicted using the present model. Resonant speeds are investigated, at which modes appear as a stationary displacement pattern to a space-fixed observer. The exact satisfaction of boundary conditions at the inner and outer ring surfaces together with the through-thickness variation of the radial and shear stresses are shown to be of significant importance when the ring rotates at high speeds or is supported by relatively stiff foundation.
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Filippi, Matteo, Alfonso Pagani, and Erasmo Carrera. "Three-Dimensional Solutions for Rotor Blades Using High-Order Geometrical Nonlinear Beam Finite Elements." Journal of the American Helicopter Society 64, no. 3 (July 1, 2019): 1–10. http://dx.doi.org/10.4050/jahs.64.032005.
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This paper proposes a geometrically nonlinear three-dimensional formalism for the static and dynamic study of rotor blades. The structures are modeled using high-order beam finite elements whose kinematics are input parameters of the analysis. The displacement fields are written using two-dimensional Taylor- and Lagrange-like expansions of the cross-sectional coordinates. As far as the Taylor-like polynomials are concerned, the linear case is similar to the first-order shear deformation theory, whereas the higher-order expansions include additional contributions that describe the warping of the cross section. The Lagrange-type kinematics instead utilizes the displacements of certain physical points as degrees of freedom. The inherent three-dimensional nature of the Carrera unified formulation enables one to include all Green–Lagrange strain components as well as all coupling effects due to the geometrical features and the three-dimensional constitutive law. A number of test cases are considered to compare the current solutions with experimental and theoretical results reported in terms of large deflections/rotations and frequencies related to small amplitude vibrations.
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Corigliano, Pasqualino. "On the Compression Instability during Static and Low-Cycle Fatigue Loadings of AA 5083 Welded Joints: Full-Field and Numerical Analyses." Journal of Marine Science and Engineering 10, no. 2 (February 5, 2022): 212. http://dx.doi.org/10.3390/jmse10020212.
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The aim of this scientific work was to evaluate the compression instability effects during static and low-cycle fatigue loadings of AA 5083 welded joints, commonly used in marine structures. Low-cycle fatigue assessment in marine structures is of utmost importance since high levels of plastic deformation can arise in the proximity of high-stress concentration areas. Displacement ratios equal to minus one and zero were used to perform experimental low-cycle fatigue tests. The tests were monitored by means of the Digital Image Correlation technique in order to detect the strain patterns, with particular attention paid to stress concentration areas, indicating that a specimen tends to buckle during high compression loads, for tests with a displacement ratio of minus one. The tests at displacement ratios equal to −1 showed a lowering of the strain–life curve revealing a considerable effect on compression instability. A nonlinear finite element modelling procedure, depending only on hardness measurements, was developed. The hardness measurements were used in order to assess the distinct mechanical properties of the different zones that were included in the finite element model. The finite element model results were compared to the data achieved by means of the digital image correlation technique, demonstrating that hardness measurements can help predict the low-cycle fatigue behaviour of welded joints and consider compression instability phenomena.
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Pradille, Christophe, Michel Bellet, and Yvan Chastel. "A Laser Speckle Method for Measuring Displacement Field. Application to Resistance Heating Tensile Test on Steel." Applied Mechanics and Materials 24-25 (June 2010): 135–40. http://dx.doi.org/10.4028/www.scientific.net/amm.24-25.135.
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Strain field measurement with non intrusive techniques is needed in order to characterize the behaviour of steels at high temperatures subjected to small displacements. In this work we present a technique based on laser-produced speckles coupled with a cross-correlation cross-spectrum method. This method proves more accurate than cross-correlation for small displacements. The laser wave length used (532 nm) allows to perform strain measurements, even with heat radiation.
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Yamazaki, Takanori. "Experimental Study on Dynamic Behavior of High Precision Servo Motor for Machine Tools." Applied Mechanics and Materials 863 (February 2017): 224–28. http://dx.doi.org/10.4028/www.scientific.net/amm.863.224.
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In the field of machining industries it is always required to improve the accuracy of precise products, die and molds. The feed drive system for the machine tools consists of an AC servo motor, an amplifier and rolling elements etc. It is well known that the nonlinear behaviors of the rolling elements influence the motion accuracy of the feed drive system. However, in spite of the analysis of static behaviors have been done, the dynamic behaviors are not so examined. Our special interest is how to control the nonlinear behaviors of the rolling elements and to operate the feed drive system with high accuracy. In order to model the nonlinear behaviors of the feed drive system, we measure the transient response when the step inputs of microscopic displacement are input to the AC servo motor and the detail analysis will be done. Experimental results show that the step responses become slow as the input displacement becomes microscopic. It means that with the ball bearing built into the AC servo motor used to feed driving system have the nonlinear behavior in microscopic displacement range.
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Ahmadinejad, Mahmoud, Alireza Jafarisirizi, and Reza Rahgozar. "Effects of Shape Memory Alloys on Response of Steel Structural Buildings within Near Field Earthquakes Zone." Civil Engineering Journal 6, no. 7 (July 1, 2020): 1314–27. http://dx.doi.org/10.28991/cej-2020-03091550.
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Base isolation is one of the effective ways for controlling civil engineering structures in seismic zone which can reduce seismic demand. Also is an efficient passive control mechanism that protects its superstructure during an earthquake. However, residual displacement of base-isolation systems, resulting from strong ground motions, remain as the main obstacle in such system’s serviceability after the earthquake. Shape Memory Alloys (SMA) is amongst the newly introduced smart materials that can undergo large nonlinear deformations with considerable dissipation of energy without having any permanent displacement afterward. This property of SMA may be utilized for designing of base isolation system to increase the structure’s serviceability. Here, a proposed semi-active isolation system combines laminated rubber bearing system with shape memory alloy, to take advantage of SMAs high elastic strain range, in order to reduce residual displacements of the laminated rubber bearing. Merits of the system are demonstrated by comparing it to common laminated rubber bearing isolation systems. It is found that the optimal application of SMAs in base-isolation systems can significantly reduce bearings’ residual displacements. In this study, OpenSees program for a three dimensional six-storey steel frame building has been used by locating the isolators under the columns for investigating the feasibility of smart base isolation systems, i.e., the combination of traditional Laminated Rubber Bearing (LRB) with the SMA, in reducing the structure’s isolated-base response to near field earthquake records are examined. Also, a new configuration of SMAs in conjunction with LRB is considered which make the system easier to operate and maintain.
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Chang, Jeng-Shian, and U.-JEI Tin. "Free vibration of antisymmetric laminates under uniform temperature field according to transverse shear and normal deformable high order displacement theory." Advanced Composite Materials 1, no. 4 (January 1991): 291–308. http://dx.doi.org/10.1163/156855191x00171.
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Wu, Wen Xiang, and Dong Zhang. "The Oil Displacement Mechanism of Viscoelastic of High-Concentration Polymer in Lamadian Oilfield." Applied Mechanics and Materials 522-524 (February 2014): 1558–61. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.1558.
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The field test of high-concentration displacement is implemented in Lamadian Oilfield North West Block. The value of enhanced oil recovery in the central area is up to 20 percent or more. In order to explore the reason of good stimulation effect of high concentration polymer flooding in Lamadian Oilfield, the mechanism of high concentration polymer systems for EOR is conducted in this paper. The high concentration is characterized by the viscosity and elasticity of polymer in this article. The results showed that: the concentration of polymer with 25 million molecular weight reach to 3000mg/L, the increases value of viscoelasticity is the largest. So high-concentration polymer is defined as 3000mg/L. Compared with conventional polymer flooding, high concentration polymer has a greater ability to expand swept volume and effectiveness of wash oil.
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Dall’Asta, E., V. Ghizzardi, R. Brighenti, E. Romeo, R. Roncella, and A. Spagnoli. "New experimental techniques for fracture testing of highly deformable materials." Frattura ed Integrità Strutturale 10, no. 35 (December 29, 2015): 161–71. http://dx.doi.org/10.3221/igf-esis.35.19.
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A new experimental method for measuring strain fields in highly deformable materials has been developed. This technique is based on an in-house developed Digital Image Correlation (DIC) system capable of accurately capturing localized or non-uniform strain distributions. Thanks to the implemented algorithm based on a Semi-Global Matching (SGM) approach, it is possible to constraint the regularity of the displacement field in order to significantly improve the reliability of the evaluated strains, especially in highly deformable materials. Being originally introduced for Digital Surface Modelling from stereo pairs, SGM is conceived for performing a one-dimensional search of displacements between images, but here a novel implementation for 2D displacement solution space is introduced. SGM approach is compared with the previously in-house developed implementation based on a local Least Squares Matching (LSM) approach. A comparison with the open source code Ncorr and with some FEM results is also presented. The investigation using the present DIC method focuses on 2D full-field strain maps of plain and notched specimens under tensile loading made of two different highly deformable materials: hot mix asphalt and thermoplastic composites for 3D-printing applications. In the latter specimens, an elliptical hole is introduced to assess the potentiality of the method in experimentally capturing high strain gradients in mixed-mode fracture situations.
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Rezaiee-Pajand, Mohammad, Nima Gharaei-Moghaddam, and Mohammadreza Ramezani. "Higher-order assumed strain plane element immune to mesh distortion." Engineering Computations 37, no. 9 (April 13, 2020): 2957–81. http://dx.doi.org/10.1108/ec-09-2019-0422.
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Purpose This paper aims to propose a new robust membrane finite element for the analysis of plane problems. The suggested element has triangular geometry. Four nodes and 11 degrees of freedom (DOF) are considered for the element. Each of the three vertex nodes has three DOF, two displacements and one drilling. The fourth node that is located inside the element has only two translational DOF. Design/methodology/approach The suggested formulation is based on the assumed strain method and satisfies both compatibility and equilibrium conditions within each element. This establishment results in higher insensitivity to the mesh distortion. Enforcement of the equilibrium condition to the assumed strain field leads to considerably high accuracy of the developed formulation. Findings To show the merits of the suggested plane element, its different properties, including insensitivity to mesh distortion, particularly under transverse shear forces, immunities to the various locking phenomena and convergence of the element are studied. The obtained results demonstrate the superiority of the suggested element compared with many of the available robust membrane elements. Originality/value According to the attained results, the proposed element performs better than the well-known displacement-based elements such as linear strain triangular element, Q4 and Q8 and even is comparable with robust modified membrane elements.
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Yang, Qiaohong, Bing Wang, and Wenhua Guo. "Effects of Large-Diameter Shield Tunneling on the Pile Foundations of High-Speed Railway Bridge and Soil Reinforcement Schemes." Symmetry 14, no. 9 (September 13, 2022): 1913. http://dx.doi.org/10.3390/sym14091913.
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In order to study the effects induced by large-diameter shield tunneling on the internal force and displacement of adjacent high-speed railway bridge pile foundations, symmetrical element analysis models for the whole process of large-diameter shield tunneling through the high-speed railway bridge were established. The protective effects of various soil reinforcement schemes such as isolation piles’ protection, Metro Jet System (MJS) reinforcement, and the addition of isolated piles’ crown beams were investigated. The numerical results show that the maximum bending moment and the maximum lateral displacement of the bridge piles appear at the piles’ body of the central elevation of the tunnel and the piles’ top, respectively. Without any soil reinforcement measures, the maximum lateral displacement and settlement of the piers top were 7.1 mm and −7.2 mm respectively, which could not meet the displacement control requirements of ±2 mm for the piers of the existing bridge under the condition of the normal operation of high-speed trains. The isolation piles’ protection effect was better than that of MJS reinforcement alone. Two or more soil reinforcement measures could be adopted simultaneously to further control the displacement of piers within ±1 mm. The validity of the numerical simulation results was verified by comparing them with the field monitoring results.
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Wang, Wei Zhuo, John E. Mottershead, Amol Patki, and Eann A. Patterson. "Construction of Shape Features for the Representation of Full-Field Displacement/Strain Data." Applied Mechanics and Materials 24-25 (June 2010): 365–70. http://dx.doi.org/10.4028/www.scientific.net/amm.24-25.365.
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The achievement of high levels of confidence in finite element models involves their validation using measured responses such as static strains or vibration mode shapes. A huge amount of data with a high level of information redundancy is usually obtained in both the detailed finite element prediction and the full-field measurements so that achieving a meaningful validation becomes a challenging problem. In order to extract useful shape features from such data, image processing and pattern recognition techniques may be used. One of the most commonly adopted shape feature extraction procedures is the Fourier transform in which the original data may be expressed as a set of coefficients (coordinates) of the decomposition kernels (bases) in the feature space. Localised effects can be detected by the wavelet transform. The acquired shape features are succinct and therefore simplify the model validation, based on the full-field data, allowing it to be achieved in a more effective and efficient way. In this paper, full-field finite element strain patterns of a plate with a centred circular hole are considered. A special set of orthonormal shape decomposition kernels based on the circular Zernike polynomials are constructed by the Gram-Schmidt orthonormalization process. It is found that the strain patterns can suitably be represented by only a very small number of shape features from the derived kernels.
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Lu, Shizhou, Wei Liu, Chenyu Zhu, Qiang Zhai, and Renshui Cao. "Precision Displacement Control of a Diamond-shaped Amplifying Mechanism Driven by Piezoelectric Actuator Based on Fuzzy Fractionalorder PIλDμ Controller." Current Nanoscience 15, no. 6 (October 11, 2019): 596–605. http://dx.doi.org/10.2174/1573413715666181212141714.
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Background: As a high-performance functional material, stacked piezoelectric actuator can produce a displacement under the effect of changing voltage. Its advantages of fast response and easy operation make it to be widely applied in the precision structure field. However, its small displacement stroke and hysteresis nonlinearity affect the accuracy of the output. : In the next step, some experiments were undertaken based on the constructed platform. Methods: In order to enlarge the displacement of piezoelectric actuator and reduce the influence of hysteresis, this study designs a diamond-shaped amplifying mechanism to amplify the output of the piezoelectric actuator, and then develops a self-tuning fuzzy fractional-order PIλDμ controller for the high precision displacement control of the proposed amplifying mechanism. After analyzing the working principle and modeling the amplifying mechanism, the fractional-order PIλDμ control model of the proposed mechanism was built and discretized according to the theoretical base of the fractional calculus in the time domain. Moreover, the fuzzy control algorithm was also introduced to achieve self-turning of parameters. Besides, the amplifying mechanism was also adopted for a microdroplet jetting dispenser to verify the practicability of the mechanism and control strategy. In the next step, some experiments were undertaken based on the constructed platform. Results: Experiments show that the displacement overshoots, the times of reaching a steady state of the traditional integer-order controller and the fractional-order controller are 5.08%, 1.17% and 17.25 s, 12.00 s, respectively. However, the fuzzy PIλDμ controller lowers the overshoot and the time of reaching a steady state to 0.95% and 9.00 s, respectively. The control algorithm can not only improve the follow-ability of the output displacement of the proposed mechanism, but also maintain the deviation within the range of 0.4% after the displacement stroke is stable and reduce the entering time of the mechanism up to 47.8%. In actual application, the droplet volume of micro-droplet jetting dispenser under fuzzy fractional-order PID control method is more stable, and its repeatability accuracy can reach up to 1.6475%. Conclusion: Experimental results indicate that the self-tuning fuzzy fractional-order PIλDμ controller can significantly improve the tracking performances of the PID and the integer-order PID with regard to the amplifying mechanism with the advantages of good dynamic character and regulation precision. Furthermore, the diamond-shaped amplification mechanism and control strategy can be applied for some micro-droplet jetting dispensers used in microelectronic packaging, life science and 3D printing fields.
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Assier, Raphaël C., Marie Touboul, Bruno Lombard, and Cédric Bellis. "High-frequency homogenization in periodic media with imperfect interfaces." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2244 (December 2020): 20200402. http://dx.doi.org/10.1098/rspa.2020.0402.
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In this work, the concept of high-frequency homogenization is extended to the case of one-dimensional periodic media with imperfect interfaces of the spring-mass type. In other words, when considering the propagation of elastic waves in such media, displacement and stress discontinuities are allowed across the borders of the periodic cell. As is customary in high-frequency homogenization, the homogenization is carried out about the periodic and antiperiodic solutions corresponding to the edges of the Brillouin zone. Asymptotic approximations are provided for both the higher branches of the dispersion diagram (second-order) and the resulting wave field (leading-order). The special case of two branches of the dispersion diagram intersecting with a non-zero slope at an edge of the Brillouin zone (occurrence of a so-called Dirac point) is also considered in detail, resulting in an approximation of the dispersion diagram (first-order) and the wave field (zeroth-order) near these points. Finally, a uniform approximation valid for both Dirac and non-Dirac points is provided. Numerical comparisons are made with the exact solutions obtained by the Bloch–Floquet approach for the particular examples of monolayered and bilayered materials. In these two cases, convergence measurements are carried out to validate the approach, and we show that the uniform approximation remains a very good approximation even far from the edges of the Brillouin zone.
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Han, Yaodong, Kai Ni, Xinghui Li, Guanhao Wu, Kangning Yu, Qian Zhou, and Xiaohao Wang. "An FPGA Platform for Next-Generation Grating Encoders." Sensors 20, no. 8 (April 16, 2020): 2266. http://dx.doi.org/10.3390/s20082266.
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Among various nanometer-level displacement measurement methods, grating interferometry-based linear encoders are widely used due to their high robustness, relatively low cost, and compactness. One trend of grating encoders is multi-axis measurement capability for simultaneous precision positioning and small order error motion measurement. However, due to both lack of suitable hardware data processing platform and of a real-time displacement calculation system, meeting the requirements of real-time data processing while maintaining the nanometer order resolutions on all these axes is a challenge. To solve above-mentioned problem, in this paper we introduce a design and experimental validation of a field programmable gate array (FPGA)-cored real-time data processing platform for grating encoders. This platform includes the following functions. First, a front-end photodetector and I/V conversion analog circuit are used to realize basic analog signal filtering, while an eight-channel parallel, 16-bit precision, 200 kSPS maximum acquisition rate Analog-to-digital (ADC) is used to obtain digital signals that are easy to process. Then, an FPGA-based digital signal processing platform is implemented, which can calculate the displacement values corresponding to the phase subdivision signals in parallel and in real time at high speed. Finally, the displacement result is transferred by USB2.0 to the PC in real time through an Universal Asynchronous Receiver/Transmitter (UART) serial port to form a complete real-time displacement calculation system. The experimental results show that the system achieves real-time data processing and displacement result display while meeting the high accuracy of traditional offline data solution methods, which demonstrates the industrial potential and practicality of our absolute two-dimensional grating scale displacement measurement system.
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Liu, Yang, Kefei Song, Xiaodong Wang, Bo Chen, Junlin Ma, and Zhenwei Han. "Displacement Analysis of Solar Magnetic Field Images in EUV Wavelengths of Space Solar Telescope." International Journal of Pattern Recognition and Artificial Intelligence 33, no. 03 (February 19, 2019): 1950005. http://dx.doi.org/10.1142/s0218001419500058.
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In this paper, the combination of nonlinear gradient iteration and crossing method is presented in order to analyze high precision remote sensing images of solar magnetic field in extreme ultraviolet (EUV) wavelengths which are usually affected by solar magnetic evolution, satellite attitude changes and random satellite jitter, and to reduce structural complexity the complicated correlation tracker is normally adopted. Using crossing method which better approached the inefficiency by computing full-scale solar magnetic field images, nine point areas are uniformly selected in full-scale solar magnetic field images which solves the problem of low-computing efficiency. Meanwhile, nonlinear gradient iteration algorithm through numerical simulation experiments is adopted to analyze displacement of solar magnetic field images in EUV wavelengths, which reduces the errors due to the solar intensity changing and tiny deformation of solar magnetic field compared to traditional algorithms. The results clearly indicate that the precision of mean error field and square deviation field for deformed displacement are both less than 5% of pixel by solar magnetic field images of Solar Dynamics Observatory (SDO).
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Ertop, Ozan, Bedri Gurkan Sonmez, and Senol Mutlu. "Displacement Sensor with Inherent Read-Out Circuit Using Water-Gated Field Effect Transistor (WG-FET)." Proceedings 2, no. 13 (November 26, 2018): 926. http://dx.doi.org/10.3390/proceedings2130926.
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This paper presents, for the first time, a displacement sensor with inherent read-out circuit using an inverter built with WG-FET that has 16-nm-thick single crystalline silicon film. In WG-FET, electrical double layer (EDL) capacitances are formed at water/silicon and water/top gate interfaces. These two capacitances and the resistance of the de-ionized (DI) water droplet build a first order RC network. Propagation delay of an inverter built with WG-FET depends on this RC constant. When the distance between top gate and silicon film changes, EDL capacitances remain the same, but resistance of the DI-water droplet changes. Accordingly, propagation delay of the inverter changes linearly with this distance. Increasing the distance from 400 µm to 1200 µm changes low-to-high propagation delay tplh of the inverter from 1.08 ms to 1.36 ms and high-to-low propagation delay tphl from 0.48 ms to 0.56 ms, which yields sensitivities of 0.35 µs/µm and 0.1 µs/µm, respectively.
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Khoa, Ngo Nhu, and Ngo Ich Thinh. "On a bending problem of thick laminated composite plates." Vietnam Journal of Mechanics 24, no. 1 (March 31, 2002): 35–45. http://dx.doi.org/10.15625/0866-7136/24/1/6607.
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A high-order displacement field in quadrilateral element with nine nodes and twelve-degrees-of-freedom per node is developed for bending analysis of thick arbitrary layered composite plates under transverse loads. Results for plate deformations, internal stress-resultants and stresses for selected examples are shown to compare well with the closed-form and other finite element solutions.
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Lampeas, George, Vasilis Pasialis, Thorsten Siebert, Mara Feligiotti, and Andrea Pipino. "Validation of Impact Simulations of a Car Bonnet by Full-Field Optical Measurements." Applied Mechanics and Materials 70 (August 2011): 57–62. http://dx.doi.org/10.4028/www.scientific.net/amm.70.57.
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Innovative designs of transport vehicles need to be validated in order to demonstrate reliability and provide confidence. The most common approaches to such designs involve simulations based on Finite Element (FE) analysis, used to study the mechanical response of the structural elements during critical events. These simulations need reliable validation techniques, especially if anisotropic materials, such as fibre reinforced polymers, or complex designs, such as automotive components are considered. It is normal practice to assess the accuracy of numerical results by comparing the predicted values to corresponding experimental data. In this frame, the use of whole field optical techniques has been proven successful in the validation of deformation, strain, or vibration modes [1]. The strength of full-field optical techniques is that the whole displacement field can be visualized and analyzed. By using High Speed cameras, the Digital Image Correlation (DIC) method can be applied to highly non-linear dynamic events and deliver quantitative information about the three-dimensional displacement field [2].
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Dagwal, V. J., D. D. Pawar, Y. S. Solanke, and H. R. Shaikh. "Tilted universe with big rip singularity in Lyra geometry." Modern Physics Letters A 35, no. 24 (June 23, 2020): 2050196. http://dx.doi.org/10.1142/s0217732320501965.
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We have examined tilted cosmological models by using conformally flat space-time with wet dark fluid in Lyra geometry. In order to solve the field equations we have considered a power law. In this paper we have discussed tilted universe with time-dependent displacement field vector, heat conduction vectors and also discussed big rip singularity. Some physical and geometrical properties are also investigated. We have also extended our work to investigate the consistency of the derived model with observational parameter from the point of astrophysical phenomenon such as look-back time-redshift, proper distance, luminosity distance, angular-diameter distance and distance modulus.
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Dai, Yao, and Xiao Chong. "The Higher Order Mechanical and Electric Fields for Arbitrarily Oriented Crack with the Physical Weak-Discontinuity." Applied Mechanics and Materials 602-605 (August 2014): 283–86. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.283.
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The higher order crack-tip fields for anti-plane crack oblique to the interface between functionally graded piezoelectric materials (FGPMs) and homogeneous piezoelectric materials (HPMs) are presented. The crack is oriented in arbitrary direction. The crack surfaces are assumed to be electrically impermeable. The material properties of FGPMs are assumed to be linear functions with their gradient direction perpendicular to the interface. By using the eigen-expansion method, the high order crack tip stress and electric displacement fields are obtained. The analytic expressions of the stress intensity factors and the electric displacement intensity factors are derived.
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YANG, Yonglin, Xing LI, Shenghu DING, and Wenshuai WANG. "A Numerical Algorithm for Arbitrary Real-Order Hankel Transform." Wuhan University Journal of Natural Sciences 27, no. 1 (March 2022): 26–34. http://dx.doi.org/10.1051/wujns/2022271026.
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The Hankel transform is widely used to solve various engineering and physics problems, such as the representation of electromagnetic field components in the medium, the representation of dynamic stress intensity factors, vibration of axisymmetric infinite membrane and displacement intensity factors which all involve this type of integration. However, traditional numerical integration algorithms cannot be used due to the high oscillation characteristics of the Bessel function, so it is particularly important to propose a high precision and efficient numerical algorithm for calculating the integral of high oscillation. In this paper, the improved Gaver-Stehfest (G-S) inverse Laplace transform method for arbitrary real-order Bessel function integration is presented by using the asymptotic characteristics of the Bessel function and the accumulation of integration, and the optimized G-S coefficients are given. The effectiveness of the algorithm is verified by numerical examples. Compared with the linear transformation accelerated convergence algorithm, it shows that the G-S inverse Laplace transform method is suitable for arbitrary real order Hankel transform, and the time consumption is relatively stable and short, which provides a reliable calculation method for the study of electromagnetic mechanics, wave propagation, and fracture dynamics.
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Bruner, Ilan, and Eugeny Landa. "Fault interpretation from high‐resolution seismic data in the northern Negev, Israel." GEOPHYSICS 56, no. 7 (July 1991): 1064–70. http://dx.doi.org/10.1190/1.1443117.
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Detection and investigation of fault zones are important tools for tectonic analysis and geological studies. A fault zone inferred on high‐resolution seismic lines has been interpreted using a method of detection of diffracted waves utilizing the main kinematic and dynamic properties of the wavefield. The application of the method to field data from the northern Negev in Israel shows that it provides a good estimate of results and, when used in conjunction with the final stacked data, can give the suspected location of the fault, its sense (reverse or normal), and the amount of “low amplitude” displacement (in an order of the wavelength or even less).
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SPESSOT, A., S. FRABBONI, R. BALBONI, and A. ARMIGLIATO. "Method for determination of the displacement field in patterned nanostructures by TEM/CBED analysis of split high-order Laue zone line profiles." Journal of Microscopy 226, no. 2 (May 2007): 140–55. http://dx.doi.org/10.1111/j.1365-2818.2007.01760.x.
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Alatza, Stavroula, Ioannis Papoutsis, Demitris Paradissis, Charalampos Kontoes, Gerassimos A. Papadopoulos, and Costas Raptakis. "InSAR Time-Series Analysis for Monitoring Ground Displacement Trends in the Western Hellenic Arc: The Kythira Island, Greece." Geosciences 10, no. 8 (July 31, 2020): 293. http://dx.doi.org/10.3390/geosciences10080293.
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Kythira Island is situated at the western Hellenic Arc, which is a region of very high seismicity and tectonic activity. On 8 January 2006, a large seismic event of Mw = 6.7 occurred close to Kythira, in association with the Hellenic subduction zone. We present an extensive multi-temporal interferometry study of ground displacements in Kythira Island exploiting SAR data of a decade, from 2003 to 2009, and from 2015 to 2019. The line-of-sight displacement field for the 2003–2009 time period presents small-scale displacements that do not exceed −3 mm/y, identified to the East of Kythira’s airport, and 3 mm/y in the central part of the island. We exploit then Sentinel-1 data from 2015 to 2019, of both descending and ascending Sentinel-1 SAR imaging modes to decompose the line-of-sight measured deformation to vertical and east–west motion components. Higher vertical displacement rates characterize the central part of the island, with a maximum value of 5 mm/y. This short-term uplift rate exceeds by an order of magnitude the long-term geologic uplift rate of ~0.13 mm/y found in the island during the Quaternary. We discuss possible regional geophysical explanations for this discrepancy. Strike-slip components are detected in the N–E coast of the Potamos village, where horizontal displacements occur, with an east-ward trend and a maximum value of −3 mm/y. These insights are valuable input for the systematic monitoring of this high seismic risk island and the dynamic assessment of its hazard potential.
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Voigt, I., and W. G. Drossel. "EXAMINATION OF HEAT PIPE BASED SYSTEMS FOR ENERGY-EFFICIENT REDUCTION OF THERMALLY INDUCED ERRORS IN MACHINE TOOLS." MM Science Journal 2021, no. 3 (June 30, 2021): 4713–20. http://dx.doi.org/10.17973/mmsj.2021_7_2021080.
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Variable heat sources in machine tools lead to unsteady displacement fields and hence necessitate temperature control in order to maintain the required positioning accuracy. Adding passive components that redistribute heat through heat storage and heat transport within the machine tool is one approach to compensate for thermal errors. While including latent heat storage components reduces the machine response to heat inputs in a certain temperature range, highly conductive elements like heat pipes provide the option to transport heat losses to environmental air or further components. Thereby, the temperature field around heat emitting machine components can be altered aiming for a reduction of thermal displacements of the tool center point. In order to guarantee the efficacy of corresponding compensation systems in machine tools, the performance of heat pipes under accelerating forces has to be determined. The present paper presents findings of experimental investigations on translationally moved heat pipes conducted on a linear direct drive based test rig. A simulation approach for modeling the heat transfer limits of heat pipes is proposed providing a high compatibility with finite element models. Different scenarios for the use of heat pipes in machine tools are demonstrated and evaluated by means of numerical results.
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Lashkari, Mohammad Javad, and Omid Rahmani. "Bending analysis of sandwich plates with composite face sheets and compliance functionally graded syntactic foam core." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 20 (November 14, 2016): 3606–30. http://dx.doi.org/10.1177/0954406215616417.
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In this paper, the problem of a rectangular plate with functionally graded soft core and composite face sheets is considered using high order sandwich plate theory. This theory applies no assumptions on the displacement and stress fields in the core. Face sheets were treated using classical theory and core was exposed to the theory of elasticity. Governing equations and boundary conditions are derived using principle of virtual displacement and the governing equations are based on eight primary variables including six displacements and two shear stresses. This solution is able to present localized displacements and stresses in places where concentrated loads are exerted to the structure since the displacements in the core can take a nonlinear form which could not be seen in the previous theories such as classical and higher order shear theories. This theory is suitable for rectangular plates under all types of loadings distributed or concentrated which can be different on upper and lower face sheets at the same point. The results were compared with the published literature using theory of elasticity and showed good agreement confirming the accuracy of the present theory. Subsequently, the solution for the core with functionally graded material is presented and effectively indicates positive role of functionally graded core.
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Wu, Di, and Bao Sheng Zhao. "A Refined Theory of Axisymmetric Thermoelastic Circular Cylinder with Transversely Isotropic." Advanced Materials Research 622-623 (December 2012): 1611–15. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.1611.
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For analyzing the exact stress field, the exact displacement field and the exact temperature field in axisymmetric thermoelastic circular cylinder with transversely isotropic, the refined theory of an axisymmetric circular cylinder was researched. Without ad hoc assumptions, the refined equation of an axisymmetric thermoelastic circular cylinder with transversely isotropic was obtained, which yields Bessel's function and the solution of the cylinder directly from the general solution. By dropping terms of high order, the approximate solutions are derived for a circular cylinder under radial direction surface loading. At last, we study the approximate equations with the temperature effect.
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Le, Canh V., and Phuc L. H. Ho. "Limit analysis of microstructures based on homogenization theory and the element-free Galerkin method." Vietnam Journal of Mechanics 42, no. 4 (December 27, 2020): 415–26. http://dx.doi.org/10.15625/0866-7136/14765.
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This paper presents a novel numerical formulation of computational homogenization analysis of materials at limit state. The fluctuating displacement field are approximated using the Element-Free Galerkin (EFG) meshless method. The estimated yield surface of materials can be determined by handling the multiscale (macro-micro) transition. Taking advantage of high-order EFG shape function and the second-order cone programming, the resulting optimization problem can be solved rapidly with the great accuracy. Several benchmark examples will be investigated to demonstrate the computational efficiency of proposed method.
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Fletcher, Lloyd, Jared Van-Blitterswyk, and Fabrice Pierron. "Combined shear/tension testing of fibre composites at high strain rates using an image-based inertial impact test." EPJ Web of Conferences 183 (2018): 02041. http://dx.doi.org/10.1051/epjconf/201818302041.
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Testing fibre composites off-axis has been used extensively to explore shear/tension coupling effects. However, off-axis testing at strain rates above 500 s-1 is challenging with a split Hopkinson bar apparatus. This is primarily due to the effects of inertia, which violate the assumption of stress equilibrium necessary to infer stress and strain from point measurements taken on the bars. Therefore, there is a need to develop new high strain rate test methods that do not rely on the assumptions of split Hopkinson bar analysis. Recently, a new image-based inertial impact test has been used to successfully identify the transverse modulus and tensile strength of a unidirectional composite at strain rates on the order of 2000 -1. The image-based inertial impact test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Thus, the purpose of this study is to modify the image-based inertial impact test method to investigate the high strain rate properties of fibre composites using an off-axis configuration. For an off-axis specimen, a combined shear/tension or shear/compression stress state will be obtained. Throughout the propagation of the stress wave, full-field displacement measurements are taken. Strain and acceleration fields are then derived from the displacement fields. The kinematic fields are then processed with the virtual fields method (VFM) to reconstruct stress averages and identify the in-plane stiffness components G12 and E22.
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Liu, Yang, Kaiwen Zhang, Denghang Tian, Liming Qu, and Yang Liu. "Research on Deep-Site Failure Mechanism of High-Steep Slope under Active Fault Creeping Dislocation." Shock and Vibration 2021 (August 19, 2021): 1–12. http://dx.doi.org/10.1155/2021/4482523.
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The reverse thrust in the deep site causes the upward propagation of stress and displacement in the overlying soil. The displacement field around the fault zone is maximum. As the spatial location becomes shallower, the soil displacement gradually becomes smaller. The deformation of the overlying soil is mainly affected by the vertical dislocation of the fracture zone. The monitoring curve showed no abrupt change value, indicating that the top surface of soil did not rupture, and only the influence of fault on the displacement transfer of the top surface of the soil. When a creeping dislocation occurs in the bottom fracture zone, the maximum principal stress of the upper boundary of the deep site is dominated by compressive stress. The maximum principal stress of the soil on both sides of the fracture zone has a maximum value, and the soil on the right side of the fracture zone has a significant compression effect. The maximum principal stress monitoring curve varies greatly, indicating the plastic failure development of soil, which is the same as the research results of the plastic failure zone in the following paper. When the bottom fracture zone starts to move, the plastic zone first appears at the junction area between the front end of the bottom fracture zone and the overlying soil. As the amount of dislocation of the fracture zone increases, the plastic zone continues to extend into the inner soil. The left and right sides of the fracture zone show tensile failure and compression failure, respectively. The development of the upper envelope curve in the plastic zone of the overlying soil satisfies the Boltzmann equation with a first-order exponential growth, while the development of the lower envelope curve satisfies the Gauss equation with a second-order exponential growth. The development curve equation of the plastic zone is verified according to the residual figures of the fitting result and the correlation parameters.